In general, displays are required to have as wide a view angle as possible so that a sharp image is visible from any view angle. In particular, liquid crystal displays, which recently have become widespread, have been under various technical developments so as to achieve a wider view angle, since liquid crystal itself has view angle dependence. However, depending on the use environment, a narrow view angle is sometimes preferable so as to allow only a user to view a display. In particular, notebook personal computers, personal digital assistants (PDAs), mobile phones, and the like are highly likely to be used in a place, such as a train and an airplane, where an indefinite number of people can be present. In such a use environment, in view of confidentiality, privacy protection, and the like, it is desirable for the display to have a narrow view angle so as not to allow nearby strangers to look in a display. Thus, there is a growing demand for one display to have a view angle that is to be switched between a wide view angle and a narrow view angle depending on the use environment. Such a demand is an issue facing not only liquid crystal displays but also any displays.
In response to the above-described demand, a technique has been proposed in which a phase difference control device is provided along with a display device for displaying an image, and a voltage to be applied to the phase difference control device is controlled, thereby changing view angle characteristics (for example, Japanese Patent No. 3322197). In Japanese Patent No. 3322197, examples of a liquid crystal mode to be used in the phase difference control liquid crystal display device include chiral nematic liquid crystal, homogeneous liquid crystal, randomly aligned nematic liquid crystal, and the like.
Also, a configuration has been disclosed conventionally in which a display liquid crystal panel and a view angle control liquid crystal panel provided thereon are sandwiched between two polarizing plates, and a voltage to be applied to the view angle control liquid crystal panel is adjusted, thereby controlling a view angle (for example, JP 10-268251 A and JP 2005-316470 A). In JP 10-268251 A, a liquid crystal mode of the view angle control liquid crystal panel is a twist nematic type. JP 2005-316470 A discloses a configuration in which the view angle control liquid crystal panel is sandwiched between two polarizing plates having transmission axes parallel to each other.